JP2625735B2 - Composite magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention uses a soft magnetic metal thin film as a main core material and an oxide magnetic material as an auxiliary core material, and exhibits characteristics particularly suitable for high-density recording. The present invention relates to a composite magnetic head.

[Summary of the Invention]

The present invention provides a composite magnetic head in which a pair of magnetic core halves at least one of which is composed of an oxide magnetic material and a soft magnetic metal thin film are abutted, and a magnetic gap is formed at the abutting portion of the soft magnetic metal thin film. The soft magnetic metal thin film is made of an Fe-Ga-Si based alloy, and a predetermined amount of oxygen is introduced into at least a portion of the soft magnetic metal thin film in contact with the oxide magnetic material, so that the magnetic properties of the soft magnetic metal thin film At the same time, the reaction at the interface between the oxide magnetic material and the soft magnetic metal thin film is suppressed, and the occurrence of a pseudo gap is suppressed.

[Conventional technology]

For example, in the field of video tape recorders (VTRs), short-wavelength recording and high-density recording are being promoted for the purpose of reducing tape width and improving image quality, and use of ferromagnetic metal powder as magnetic powder. A magnetic recording medium having a high coercive force and a high residual magnetic flux density like a so-called metal tape has been adopted.

Therefore, the core material of a magnetic head that performs recording / reproducing on this type of magnetic recording medium is required to have a high saturation magnetic flux density and maintain a high level of magnetic permeability even in a high frequency region. Have been. For example,
In magnetic heads of audio tape recorders and the like, ferrite (oxide magnetic material), which is widely used as a core material, has insufficient saturation magnetic flux density, and it is difficult to sufficiently magnetize a high coercive force magnetic recording medium.

Therefore, a so-called metal-in-gap type composite magnetic head in which ferrite is used as an auxiliary core material and a soft magnetic metal thin film having a high saturation magnetic flux density is inserted in a gap portion has been proposed. Has been adopted.

[Problems to be solved by the invention]

By the way, when a soft magnetic metal thin film having a high saturation magnetic flux density is formed as a main core material on an auxiliary core material made of an oxide magnetic material such as ferrite to form a metal-in-gap composite magnetic head. In other words, so-called waviness, in which the frequency characteristics of the reproduced signal fluctuates periodically, has been observed. This is because the high-temperature heating following the glass fusing step, which is indispensable in the manufacturing process of the magnetic head, causes the oxygen of the oxide magnetic material to migrate to the soft magnetic metal thin film, resulting in a region where the magnetic permeability is significantly reduced, that is, the reaction layer That is because Since the above-mentioned reaction layer contains an insulating oxide as a main component, it acts as a pseudo gap, reproduces a pseudo signal by causing interference with a magnetic flux in an original magnetic gap, and reproduces a signal such as undulation or deterioration of an SN ratio. The signal quality is degraded.

This tendency is particularly remarkable in a composite magnetic head in which a soft magnetic metal thin film is arranged in parallel to a magnetic gap, and hinders the practical use of this type of composite magnetic head.

In order to prevent the formation of the reaction layer, attempts have been made to form a reaction prevention layer at the interface between the soft magnetic metal thin film and the oxide magnetic material using a nonmagnetic material such as silicon oxide. In order to obtain the effect, the reaction prevention layer needs to have a certain thickness or more, and the reaction prevention layer itself may constitute a pseudo gap, which may adversely affect the reaction.

In view of the above, the present invention has been proposed in view of the above-mentioned conventional circumstances, and it is an object of the present invention to effectively suppress a reaction at an interface between an oxide magnetic material and a hard magnetic metal thin film and prevent a pseudo gap from occurring. Accordingly, it is an object of the present invention to provide a composite magnetic head capable of performing sufficient recording / reproduction even with a high coercive force magnetic recording medium and having less undulation in reproduction characteristics.

[Means for solving the problem]

The present inventor has conducted intensive studies to achieve the above-mentioned object, and as a result, in order to prevent the transfer of oxygen from the oxide magnetic material to the hard magnetic metal thin film, in advance, the vicinity of the bonding interface of the soft magnetic metal thin film was determined. It has been found that it is effective to mix a small amount of oxygen into the thin film to reduce the reducing power of the soft magnetic metal thin film, and have completed the present invention.

That is, in the composite magnetic head of the present invention, a pair of magnetic core halves at least one of which is formed of an oxidized magnetic material and a soft magnetic metal thin film are abutted, and a magnetic gap is formed at the abutting portion of the soft magnetic metal thin film. In the composite magnetic head, the soft magnetic metal thin film is made of an Fe-Ga-Si alloy, and at least a portion of the soft magnetic metal thin film that contacts the oxide magnetic material contains 0.05 to 10 atomic% of oxygen.
It is characterized by containing.

[Action]

In the composite magnetic head of the present invention, since oxygen is introduced into at least a portion of the soft magnetic metal thin film made of the Fe-Ga-Si alloy in contact with the oxide magnetic material, for example, the oxide magnetic Transfer of oxygen from the material to the soft magnetic metal thin film is suppressed, and formation of a reaction layer is suppressed.

Therefore, generation of a pseudo gap is prevented, and undulation of the frequency characteristic during recording and reproduction is eliminated.

Since the oxygen content at this time is set to 0.05 to 10 atomic%, the soft magnetic characteristics of the soft magnetic metal thin film are not impaired.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

This embodiment is an example of a composite magnetic head in which a soft magnetic metal thin film is arranged in parallel with a magnetic gap.

As shown in FIG. 1, the composite magnetic head of this embodiment
The left and right magnetic core halves (I) and (II) are formed on the left and right sides of the magnetic gap g located at the center of the magnetic recording medium facing surface. (II) are joined to face each other.

In addition, at least one of the magnetic core halves (I) and (II), [in this example, the magnetic core half (II)] includes:
A winding hole (1) around which a coil for supplying a signal to the composite magnetic head or extracting a signal is wound.
Are drilled.

FIG. 2 shows the composite magnetic head as viewed from the surface in contact with the magnetic recording medium, and shows the respective magnetic core halves (I) and (II).
Are auxiliary core portions (2) and (3) made of an oxide magnetic material such as Mn-Zn ferrite, and a soft magnetic metal thin film (4) made of a soft magnetic alloy material having a high saturation magnetic flux density and serving as a main core portion. , (5).

The auxiliary core portions (2) and (3) are cut off on both sides along the abutting surfaces of the magnetic core halves (I) and (II), and have substantially arc-shaped grooves for regulating the track width Tw. (6) and (7).

Core materials for the auxiliary cores (2) and (3) include:
An oxide magnetic material such as a ferrite material typified by the above-described Mn-Zn ferrite is used. In particular, a predetermined magnetic flux density B ₁₀ (magnetization force 1) depends on the effective gap length Gg of the magnetic gap g.
It is preferable to use a ferrite material having a magnetic flux density of 0 Oe.

The present inventors studied various ferrite materials to be used,
Magnetic flux density B ₁₀ and the effective gap length Gg of this ferrite material
And the chroma characteristics at this time were measured. The results are shown in the following table.

From this table, the magnetic flux density B ₁₀ of ferrite material for satisfying the chroma characteristics, when the effective gap length is 0.27 [mu] m 4500 (G), when the effective gap length is 0.25 [mu] m 5000
(G), it can be seen that when the effective gap length is 0.21 μm, it is 5500 (G).

Therefore, in order to satisfy the chroma characteristics, magnetic flux density F _B of the ferrite material to be used, when 0.21 ≦ Gg ≦ 0.25, when the _{F B ≧ 656.25 / Gg + 2375} 0.25 ≦ Gg ≦ 0.27, F B ≧ 1687.5 / Gg It will be preferable to be -1750.

A ferrite material having such a high magnetic flux density can be obtained by hot isostatic pressing (so-called HIP), and for example, in the case of Mn-Zn ferrite, Fe ₂ O
_{3. The} magnetic flux density can be controlled by controlling the composition of ZnO and MnO.

Further, the soft magnetic metal thin films (4) and (5) are provided with end surfaces (2a) and (3a) of the auxiliary core portions (2) and (3) on the butting surface side and grooves (6) and (7). The soft magnetic metal thin films (4) and (5) on the end faces (2a) and (3a) are butted in parallel via a gap spacer to form a magnetic gap g. Have been.

The gap spacer interposed between the soft magnetic metal thin films (4) and (5) may be formed by sputtering silicon oxide (SiO ₂ ) or the like, or the fused glass may function as a gap spacer. It may be.

Further, in the space formed by the grooves (6) and (7) provided in the auxiliary cores (2) and (3), the contact characteristics with the magnetic recording medium are ensured and the magnetic recording medium is slidably contacted. Non-magnetic material such as glass material is filled in order to prevent uneven wear due to non-magnetic material, and the non-magnetic material filling portions (8), (9)
It has become.

For the soft magnetic metal thin films (4) and (5), a soft magnetic alloy material having a high saturation magnetic flux density and excellent soft magnetic properties is used, and an Fe-Ga-Si alloy is used.

Here, the soft magnetic metal thin films (4) and (5) may form a non-magnetic reaction layer at the joint interface with the auxiliary cores (2) and (3). The vicinity of the interface contains oxygen. Of course, the soft magnetic metal thin films (4) and (5) may contain oxygen not only in the vicinity of the bonding interface but also throughout the soft magnetic metal thin films (4) and (5). Needless to say.

As a method for introducing oxygen into the soft magnetic metal thin films (4) and (5), oxygen is introduced into a sputtering atmosphere when the soft magnetic metal thin films (4) and (5) are formed by sputtering. It should be left.

As the sputtering method, any method may be used as long as it is usually performed, such as bipolar direct current sputtering, tripolar sputtering, quadrupolar sputtering, magnetron sputtering,
Any of techniques such as high frequency sputtering, bias sputtering, asymmetrical AC sputtering, opposed target sputtering, and ion sputtering can be employed.

The gas pressure during sputtering is 1 × 10 ⁻⁴ Torr to 2.0 × 1
Preferably, it is in the range of 0 ^-1 Torr. This gas pressure is 2.0
If it exceeds × 10 ⁻¹ Torr, the sputtering speed will be low, which is not practical.

In the above sputtering, oxygen is contained in an inert gas (He, Ne, Ar, etc.) in a sputtering atmosphere of 0.01 to 40% by volume.
The oxygen is introduced into the soft magnetic metal thin film to be mixed and formed. When oxygen is mixed into the whole of the soft magnetic metal thin films (4) and (5), the sputtering may be continued in the atmosphere in which the oxygen is introduced, and the auxiliary core portion (2),
In the case where oxygen is mixed only in the vicinity of the bonding interface with (3), sputtering is performed in an atmosphere in which oxygen is introduced for a while after the start of film formation, and then the introduction of oxygen is stopped and sputtering is continued.

Actually, as a material of the soft magnetic metal thin films (4) and (5), Fe
-Ga-Si-Ru-based crystalline alloy was selected, and the relationship between the amount of oxygen in the sputtering atmosphere and the thickness of the reaction layer and the relationship between the amount of oxygen and the undulation of the frequency characteristics during recording / reproducing were determined.
The result as shown in the figure was obtained.

As is apparent from FIG. 3, the effect of reducing the reaction layer at the interface between the ferrite and the soft magnetic metal thin film is due to the fact that the oxygen content is 5%.
It is remarkable at the volume% or more, and the swell of the frequency characteristic is also eliminated.

The effect of the thickness of the reaction layer generated at the interface between the ferrite and the soft magnetic metal thin film on the frequency characteristics during recording and reproduction is as follows.
It is clear from the following experiment.

First, the state of the ferrite-metal interface in the pseudo gap portion was examined with respect to frequency characteristics having large and small undulations. As a method, observation with an electron microscope and analysis of Auger composition near the interface were performed.

As a result, in the observation with an electron microscope, no reaction layer was observed at the interface between the ferrite and the soft magnetic metal thin film when the undulation was small, but when the undulation was large due to the reaction between the ferrite and the soft magnetic metal thin film. An altered layer (reactive layer), which is considered to have been observed, was observed. According to Auger analysis, those with large undulations show Ga in the composition of the soft magnetic metal thin film near the interface.
Was found to be distributed in large numbers. Therefore, the change in composition due to the reaction of this part deteriorates the magnetic properties,
It can be said that it is a pseudo gap.

The effect of the pseudo gap is determined by the ratio of the efficiency to the main gap (magnetic gap g), and the soft magnetic metal thin film (4),
When (5) has a parallel film structure, the gap length ratios are equivalent. That is, assuming that this ratio is K, K = the efficiency of the pseudo gap / the efficiency of the main gap = the pseudo gap length / the main gap length. Here, the smaller the K is, the less the effect of the pseudo gap is. When the relationship between K and the value of the swell is examined from computer simulations and measured values, the amount of swell increases sharply from around K = 1/3. Therefore,
It can be said that the thickness of the reaction layer is preferably 1/3 or less of the magnetic gap g.

The soft magnetic metal thin films (4) and (5) formed by performing sputtering in an atmosphere containing oxygen contain oxygen in the films. Therefore, the composition of the Fe—Ga—Si based alloy is Fe _a Ga _b Si _c ... (1) (where a, b, and c each represent a composition ratio in atomic%). The composition range is 68 ≦ a ≦ 84 1 ≦ b ≦ 236 ≦ c ≦ 31 and contains 0.05 to 10 atomic% of oxygen. When the oxygen content is less than 0.05 at%, the effect of suppressing the reaction layer is not sufficiently exhibited, and when the oxygen content exceeds 10 at%, the magnetic properties of the soft magnetic metal thin film are deteriorated. The introduction of oxygen within such a range is advantageous not only in the effect of suppressing the reaction layer but also in the soft magnetic properties of the soft magnetic metal thin film, and achieves low coercive force and high magnetic permeability.

The Fe-Ga-Si-based alloy has a Ru content to improve wear resistance.
May be added up to 12 at% of the total, and up to 15 at% of Fe may be replaced by Co, Ni or both.

Furthermore, in order to improve corrosion resistance, wear resistance, etc., up to 6 atomic% of the total amount of Ga and Si is used for Ti, Cr, Mn, Zr, Nb, Mo, T
a, Ra, W, Os, Ir, Re, Ni, Pd, Pt, Hf, Y, B, In, etc.

 The same applies to each of the aforementioned soft magnetic alloy materials.

In order to introduce oxygen into the soft magnetic metal thin films (4) and (5), oxygen may be mixed in the sputtering atmosphere as described above. In addition, moisture (H ₂ O) is mixed in the sputtering atmosphere. May be formed. The amount of H ₂ O mixed is 1-2
0% by volume. Examples of a method for mixing H ₂ O include a method in which an inert gas is introduced into a container filled with pure water, and then introduced into a vacuum chamber. Thus perform the sputtering with H ₂ O mixed inert gas, H ₂ O is oxygen is incorporated into the sputtering film dissociates during sputtering.

Alternatively, the soft magnetic metal thin films (4) and (5) may be formed by performing sputtering in an atmosphere containing nitrogen together with oxygen. In this case, it is preferable that the introduction amounts of oxygen and nitrogen in the sputtering atmosphere are both in the range of 0.05 to 40% by volume. When the sputtering is performed in an atmosphere containing nitrogen as described above, the film structure of the soft magnetic metal thin film formed changes as compared with the case where the sputtering is performed using only the inert gas. The reactivity between the ferrite and the soft magnetic metal thin film is determined by the reducing ability of the soft magnetic metal thin film and the ability to diffuse oxygen in the ferrite. Oxygen diffusion depends on the structure of the soft magnetic metal thin film, particularly on the particle size (grain size) and the exposed surface area between the grains. When sputtering is performed in an atmosphere containing nitrogen gas, the resulting film becomes a dense film and the gap between grains is reduced, so that grain boundary diffusion through the gap between grains is suppressed. In addition, when nitrogen is taken into the grain boundaries, the diffusion of oxygen at the grain boundaries and the reducing ability of the soft magnetic metal thin film are reduced, so that the redox reaction between the two is further prevented.

The above-mentioned soft magnetic metal thin films (4) and (5) may be a single-layer film of a soft magnetic alloy material having a high saturation magnetic flux density, a non-magnetic material (SiO ₂ or Ta ₂ O ₅ ), or the like. It may be a laminated film with a soft magnetic ferrite film or the like. In particular, when a laminated film structure with a soft magnetic ferrite film is formed and oxygen is introduced into each soft magnetic alloy material layer, a soft magnetic metal thin film excellent in high frequency characteristics of magnetic permeability can be obtained.

In the composite magnetic head having the above configuration, since the soft magnetic metal thin films (4) and (5) have a shape converging toward the magnetic gap g, the magnetic flux can be intensively guided to the magnetic gap g. In addition to the magnetic recording medium having a high coercive force, it is possible to perform sufficient recording / reproducing, as well as the auxiliary cores (2) and (3) and the soft magnetic metal thin films (4) and (5). Since the reaction at the interface is suppressed, it is possible to eliminate the undulation of the frequency characteristics during recording and reproduction. Further, in the composite magnetic head of this embodiment, the soft magnetic metal thin films (4) and (5) are butted in parallel in the magnetic gap g. It is advantageous.

By the way, in the above embodiment, the magnetic core halves (I),
Although (II) has been described as being symmetrical when viewed from the magnetic recording medium facing surface, as shown in FIG. 4, the magnetic core halves (III) and (IV) have a bilaterally asymmetric structure. Is also good.

That is, as shown in FIG. 4, in the magnetic core half (III) on the entry side (leading side) of the magnetic recording medium, the _{one in} which the groove cutting angle α1 of the auxiliary core portion (12) is small is used. The track width accuracy is ensured by the soft magnetic metal thin film (14) deposited on the auxiliary core portion (12), and conversely, the magnetic core half (I) on the discharge side (trailing side) of the magnetic recording medium.
In V), used after reducing the grooved angle alpha ₂ of the auxiliary core portion (13), ferrite occurs mass positioned by magnetic saturation to the magnetic gap portion near composed of a soft magnetic metal thin film (15) The structure is difficult.

In this case, the groove cutting angles of the auxiliary core portions (12) and (13) of the magnetic core halves (III) and (IV) are α ₁ = 0 ° to 30 ° on the leading side and α ₂ on the trailing side. = 30 ゜ ~
Preferably it is 90 °.

With such a structure, a composite magnetic head having excellent track width accuracy and excellent recording characteristics is realized. In particular, in a composite magnetic head having a structure in which winding holes are formed in both magnetic core halves and the volumes of the auxiliary core portions on the leading and trailing sides are substantially equal, the asymmetry of the sliding surface of the magnetic recording medium is improved. The structure is valid.

As described above, specific examples of the present invention have been described.
It goes without saying that the present invention is not limited to this embodiment, but can be applied to various composite magnetic heads.

For example, in the previous embodiment, the soft magnetic metal thin films were arranged in parallel at the magnetic gap portion. However, as shown in FIG. 5 or 6, the soft magnetic metal thin films are obliquely butted in the magnetic gap. A magnetic head having a simple structure may be used.

In the composite magnetic head shown in FIG. 5, the butting surfaces of the auxiliary core portions (22) and (23) constituting the respective magnetic core halves (V) and (VI) are cut obliquely, and the soft surfaces are formed on the inclined surfaces. The magnetic metal thin films (24) and (25) are applied, and the soft magnetic metal thin films (24) and (25) are obliquely and linearly butted against each other in a magnetic gap.

FIG. 6 shows an auxiliary core part (32), which constitutes each of the magnetic core halves (VII) and (VIII), like the one shown in FIG.
The butted surface of (33) is cut obliquely, and the soft magnetic metal thin films (34) and (35) are deposited on the inclined surface. The soft magnetic metal thin films (34) and (35) Is bent at an intermediate portion to enlarge the track width of the magnetic gap.

In any of these composite magnetic heads, the soft magnetic metal thin film (24), (25) or the soft magnetic metal thin film (3
4), (35) at least the auxiliary core part (22), (23),
If oxygen is introduced into the vicinity of the joint interface with (32) and (33), the formation of a reaction layer at the joint interface is suppressed.

〔The invention's effect〕

As is clear from the above description, in the composite magnetic head of the present invention, since oxygen is introduced into at least a portion of the soft magnetic metal thin film which is in contact with the oxide magnetic material, a non-magnetic reaction occurs at these bonding interfaces. The formation of a layer can be suppressed, and the pseudo signal output due to the pseudo gap can be reduced.

Further, in the present invention, since the amount of oxygen introduced is set in an appropriate range, the soft magnetic properties of the soft magnetic metal thin film are not impaired, but rather a low coercive force and a high permeability are achieved. You.

Therefore, according to the present invention, it is possible to provide a composite magnetic head with less undulation in frequency characteristics during recording and reproduction and excellent in electromagnetic conversion characteristics.

[Brief description of the drawings]

FIG. 1 is an external perspective view showing an embodiment of a composite magnetic head to which the present invention is applied, and FIG. 2 is an enlarged plan view of a main part showing a magnetic recording medium contact surface. FIG. 3 is a characteristic diagram showing the relationship between the amount of oxygen in the sputtering atmosphere, the thickness of the reaction layer, and the undulation of the frequency characteristics during recording and reproduction. FIG. 4 is an enlarged plan view of a main part showing another example of the composite magnetic head to which the present invention is applied. FIG. 5 is an enlarged plan view of a main part showing still another example of the composite magnetic head to which the present invention is applied. FIG. 6 is an enlarged plan view of a main part showing still another example of the composite magnetic head to which the present invention is applied. I, II, III, IV, V, VI, VII, VIII ... Magnetic core half 2,3,12,13,22,23,32,33 ... Auxiliary core part 4,5,14,15,24 , 25,34,35 …… Soft magnetic metal thin film

(72) Inventor Yoshiyuki Kunigami 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Magne Products Co., Ltd. (72) Inventor Etsuo Izu 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Magne Products Co., Ltd. (72) Inventor Toshiyuki Okada 6-5-6 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Magne Products Co., Ltd. (72) Inventor Masatoshi Hayakawa Kita, Shinagawa-ku, Tokyo 6-7-35 Shinagawa Inside Sony Corporation (56) References JP-A-62-125506 (JP, A) JP-A-62-145510 (JP, A) JP-A-60-123709 (JP, U)

Claims (1)

(57) [Claims] 1. A composite magnetic head in which a pair of magnetic core halves at least one of which is composed of an oxide magnetic material and a soft magnetic metal thin film are abutted, and a magnetic gap is formed at the abutting portion of the soft magnetic metal thin film. The composite according to claim 1, wherein the soft magnetic metal thin film is made of an Fe-Ga-Si alloy, and at least a portion of the soft magnetic metal thin film that contacts the oxide magnetic material contains 0.05 to 10 atomic% of oxygen. Magnetic head.